CVE-2026-43037Public exploitNetwork attack vector

Kernel memory corruption via stale tunnel control data

Published May 1, 2026 · Updated May 1, 2026

Stack buffer overflow in Linux Kernel ip6_tunnel allows remote attackers to corrupt kernel memory via crafted ICMPv6 errors. In ip4ip6_err(), a cloned packet retains IPv6 control-block data that __ip_options_echo() misreads as IPv4 options, then uses an attacker-controlled length to copy into a 40-byte stack buffer. The path is reached by unauthenticated network input that triggers IPv4-over-IPv6 tunnel error handling; the overflow corrupts kernel memory and can crash the system.

CVSS severity9.8
Critical
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack buffer overflow in Linux Kernel ip6_tunnel allows remote attackers to corrupt kernel memory via crafted ICMPv6 errors. In ip4ip6_err(), a cloned packet retains IPv6 control-block data that __ip_options_echo() misreads as IPv4 options, then uses an attacker-controlled length to copy into a 40-byte stack buffer. The path is reached by unauthenticated network input that triggers IPv4-over-IPv6 tunnel error handling; the overflow corrupts kernel memory and can crash the system.

The record

CVE
CVE-2026-43037
Published
May 1, 2026
Updated
May 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-787, CWE-843, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 1, 2026CVE publishedPublication date reported by the CVE source.
  2. May 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.22
  2. Affected versionversion=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <1063515ce15ff31065c4e7f8265f4c2fd3c54876
  3. Affected versionversion=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <2cc6e3b0fe0f0242d1f530a93a4924f48ab85ba5
  4. Affected versionversion=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <2edfa31769a4add828a7e604b21cb82aaaa05925
  5. Affected versionversion=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <4a622658f384b03560834cbe8ffcfe69a278f7c8
  6. Affected versionversion=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <590f622669b97eaf7b57a1de7b0a6e68c5d8b2c3
  7. Affected versionversion=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <a0c4ce9900a108eaf55d0f3b399cb55999647d39
  8. Affected versionversion=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <d6621f60192fe10c047a4487be42a6f4c150707f
  9. Affected versionversion=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <ea9f65b27c8404e164848ebff1443310fd187629

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2.6.22; version=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <1063515ce15ff31065c4e7f8265f4c2fd3c54876; version=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <2cc6e3b0fe0f0242d1f530a93a4924f48ab85ba5; version=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <2edfa31769a4add828a7e604b21cb82aaaa05925; version=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <4a622658f384b03560834cbe8ffcfe69a278f7c8; version=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <590f622669b97eaf7b57a1de7b0a6e68c5d8b2c3; version=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <a0c4ce9900a108eaf55d0f3b399cb55999647d39; version=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <d6621f60192fe10c047a4487be42a6f4c150707f; version=c4d3efafcc933fd2ffd169d7dc4f980393a13796 <ea9f65b27c8404e164848ebff1443310fd187629

Published CVSS scores

9.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.8Red Hat SADPCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-843Access of Resource Using Incompatible Type ('Type Confusion')
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

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